Fishing the thermocline

I know the B.O.C. is going to get tired of me asking all these questions, but.........
I was readin something about catchin Blues where the author kept talking about finding fish at the thermocline. Now as I understand it the thermocline is the depth in the water where the temperature changes abruptly. Well......
#1. Doesn't the water temperature depend on the temperature outside?.
it just takes longer for deeper water to be heated up or cooled down
by the outside air temp. So it seems like the thermocline would be
changing all year long, getting deeper or more shallow as the seasons changed. The only way to find the thermocline is to hang a thermometer from a string and lower it overboard then check the temp at different water depth until you find an abrupt change. Well.. not being naturally inclined to do all this extra work, I checked my fish finder to find out if it had a thermocline button, it didn't. Since I had no intention of spending my day off measuring water temperatures. I started looking for bait fish (shad)on the sonar, and then fished a couple feet below the shad for Blues. Anybody have any thoughts about this thermocline idea? Any experience etc.

It drop's at excatley 33 ft. It's one atmosphere from the surface and the thermocline can be seen in the water if you dive. The water ripples when you go throw it. The fish lay down waiting for the smaller baitfish and come up to feed. You can never go wrong live lining at 32 -28 Ft.

You are correct in that the thermocline moves with the seasons. You must be familliar with the water you are fishing or start dropping the ol' meat thermometer. The main thing to remember is when stratification is evident the catfish will be found in greater concentrations within the thermocline. Why? Two reasons. First the upper layer has too much light penetration to be comfortable for the catfish and the hypolimnion (the area of water that is below the thermocline) is usually really low in oxygen. This leaves the thermocline where the light is just right and the oxygen is comfortable for the catfish.

You are correct in that the thermocline moves with the seasons. You must be familliar with the water you are fishing or start dropping the ol' meat thermometer. The main thing to remember is when stratification is evident the catfish will be found in greater concentrations within the thermocline. Why? Two reasons. First the upper layer has too much light penetration to be comfortable for the catfish and the hypolimnion (the area of water that is below the thermocline) is usually really low in oxygen. This leaves the thermocline where the light is just right and the oxygen is comfortable for the catfish.

Great Post Guys. If I ever fish a lake, I'll look you guys up for advice. We River Rats do not have a Thermocline do to the rapid current but I enjoyed reading (and learning) from your post. Good Luck Fishing.

It's true you will have shift's but the fact remain's 33 feet is your ripple effect.. Moving current will effect your thermocline, I've seen it person. It's amazing to go threw it., fish on the bottom with baitfish above.

steve w you can see the thermocline on a lcd graph. thats how i find it. to me it seems to change from lake to lake. afew years ago i was catching blues at 35ft but last year the fish where at 25 ft. i will note that the 35ft year was a dry summer, so they wherent pulling much water. i love to fish the thermocline in the summer. just drop your line down to it and drift around in the main river channel areas. i dont do as good on the bottom when there is a thermocline. i see fish on the bottom during the daytime but at night nothing on the bottom. once the lake turns over in sept here i go back to fishing the bottom. im not saying you wont catch fish on the bottom with a thermo. i just do better around it in the summer. this is how we have a striper kill off in the lakes here. some deep holes will hold oxygen in them and the stripers will go to them but the thermocline forms and traps those fish in them deep holes. they will stay there until the oxygen is gone in the hole and they die. alot of dead things go to the bottom and that takes the oxygen out as well.

i read some ware that if you take a 12 ft. stick of quarter round with about 1 pound of lead with a long line tu raise an lower it, ease it in the water an lower it down about 20 feet for a couple of min. when you pull it back up there should be a darklower end and a lighter top end, the change is suposted to be at the oxy level. they say it works, never tried it . carl

Great Post Guys. If I ever fish a lake, I'll look you guys up for advice. We River Rats do not have a Thermocline do to the rapid current but I enjoyed reading (and learning) from your post. Good Luck Fishing.

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last year the river i fish got really low and extremely hot (90 degrees!) and it actually stratified in the deeper pools. if you threw out a live bait in 15-20ft+ water, and then reeled it in after 15 minutes, your bait would be dead. never thought i'd see it but it happened.

last year the river i fish got really low and extremely hot (90 degrees!) and it actually stratified in the deeper pools. if you threw out a live bait in 15-20ft+ water, and then reeled it in after 15 minutes, your bait would be dead. never thought i'd see it but it happened.

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Thats an interesting observation dink. I suppose its possible for it to happen in stagnant water. I primarily fish the Mississippi, and its always moving fast. Even on low water conditions that current really rips. Thats some hot water. I have never observed river conditions with water that hot. A fellow couldnt even take a swim in that. Thanks for sharing your observation.

So I did a quick search to see if the thermolcline is always 33 feet. All I found is that it change though the day and season. So whats this 33 feet all about? Oh and some lakes can have 2 or more well hmm learn something new every day.